Utilizing wood waste



H, F. WEHSS UTILIZNG WOOD WASTE @riginal Filed May 19 1923 @kwam/hoz331g: if@ @Vio/wwwa Patented .lune 7, 1927.

UNITED STATES.A

PATENT OFFICE.

HOWARD F. WEIS'OF MADISON, WISCONSIN, ASSIGNOB, BiY MEBNE ASSIGNIBNTB,TO WOOD CONVERSION COMPANY, OI CLOQUET, MINNESOTA, A CORPORATION OFDELA- WARE.

UTILIZING WOOD WASTE.

application nea ny 1s, 1921, smal mi. 410,961. Renewed apra 1e, 11m.

There are now on the market three general types of wall board made fromwood. The first type is made as follows: Round wood is ground into amechanical pulp on grinding equipment such as is used 1n making ordinaryground Wood pulp for paper manufacture. To this ground wood pulp 1sadded a certain amount of chemical pulp to give added strength .to thefinished product,

"l then the mixture is flowed over an ordinary board machine into asheet of paper having the thickness of ordinary card-board. At the endof the paper making machine the sheets are wound into rolls of a sizeconlf venient for transportation. The wall board is made from them byunrolling tive Irolls or more simultaneously and gluing or cementing thevarious sheets of paper together, usually with an adhesive such assodlum 1' silicate. The sheets of paper or card-board thus glued toether are then cut to the desired size an dried and in this form arecommercial wall board. Some manufacturers use waste papers in whole orin art 3" instead of ground round wood, but wit out change in theessentials of the process as above outlined. falls boards of this typeare sold in the United States in greater tonnage than those of any othertpe. t

A second type of wall boar now on the market is made by grinding thewood to a pulp and then beating the Eulp in standard paper makingbeaters and nally flowing it into trays; these trays are then put into ahydraulic press and the mass is compressed into a dense product which isthen removed from the press, dried, trimmed, and surfaced. Chemical pulpcan be substituted in whole or iu part for ground wood pulp in this typeof board. This board consists of but one layer, and usually is denserand has a more compact surface than wall board made from paper sheets.

A third type of Wall board is made by '45 gluing or cemeuting betweentwo heavy sheets of paper, slats of wood placed side by side. This boardis expensive because of.

thel cost of the WoodV slats and because of' the relatively largequantity of sodium sili- :lo cate or other adhesive that must be used inholding the slats together and in fastening the covering sheets firmlyto the Wood. The

covering sheets are relatively tough and.

thick and have the characteristic appearance and surface texture ofpaper.

These three t pes include all of the various varieties o wood wall boardnow on the market in a large way. They all involve the step of firstpreparing a wood pulp either mechanically or chemicall in standard pulpmaking equipment. uch equipment is, from its very character, expensiveto install and expensive to operate, and requires large floor area,particularly for the driers of the pa er making machine. Furthermore,the manu acture of all of these types starts with logs `of good size andquality, which, if not used in the manufaeture of wall board, could wellbe used in the manufacture of newsprint paper and even more expensive paers. And aside from the standard pulp-ma ing equipment vused in theseprocesses, the boards themselves are made on large and expensivemachines requiring large floor area; the single exception being the oneply board made on a press as above outlined.

All of the wall boards above described rely mainly for their strengthupon the interlacing and interlocking of the libers and, therefore,their processes of manufacture aim to make a pulp having fibers as longas possible.' In general, for best results, this requires the use ofround wood of good quality and of grinding equipment well desi ned andcarefully maintained. But aroun every saw mill there accumulates largequant-ities of what may be termed saw mi such as slabs, edgingstrimmings, sawdust, shavings, and bark. ome of this material such as theslabs and'edgings, is marketable, under favorable shipping conditions,to paper mills, but though the quality of-fiber in the slabs and edgingsis as good or better than the general run of fiber from round wood, thepieces of"wood are in such physical condition that they are not readilyreduced to a/pulp, with the result that the yield of fiber is low, thequality of the pulp 1s poor, and the practical .difficulties ofoperation are enormous.

Any Wall board process that de ends for its raw material on grindingroun wood on a stone requires the expenditure of large quantities ofpower. For example, a ton ofl ground wood pulp, suitable for making thelies of a wall board, requires 1200 to 2400 oursepower hours for grmdingalone. This great quantity of power is consumed, partly in themechanical work of tearing the fibers l olal or wood waste,

one from another, but more largely in frietional loss at the surface ofthe stone Where it rubs with heav pressure on the log of wood and wherethe log acts as a brake on the stone. This frictional loss is dissipatedin the form of heat and the heat is carried away in the cooling waterand thus is lost. The cooling water, after separatlon of the fibers, isordinarily run to waste.

It is an object ol' the present invention to produce a Wall boardconsisting essentially of a single ply, this board being free fromsodium silicate, and being uniform throughout. The board may have asurface that is dense and capable of taking a good finish land even ahigh polish, and if desired, can be ornamented by graining and paintingmethods now well developed in the decoration of sheet material, such forinstance as sheet metal.

It is a further object ot the present invention to produce a wall boardof acceptable character from saw mill offal such as slabs, trimmings,edgings, sawdust, shav ings, and even bark and to do this with a powerconsumption far below that ordinarily needed and in machinery andbuildings less expensive than those now needed for the production ofwall board from ground wood or from chemical pulp. Other objects andadvantages of the present invention will become clear from the followingdescription which is to be taken in conjunction with thelaccompanyingdrawings. wherein: v

Figure 1 is a diagrammatic representation, in elevation, of a completeplant for making wall board bv the present process,

andF ig. 2 is a diagrammatic plan view of the same.

The wall board of the present invention comprises a binder and a fillerand the novelty in the product lies particularly in the binder and inits combination with a filler of special character. There .is alsonovelty in the process of making and using the binder, particularly forthe manufacture of a wall board such as that hereinafter described.

The binder consists essentially of lignoeellulose gelatinized bymechanical disintegration preferably in the presence of water andwithout the use of any gelatinizing chemical. This binder, when dry, isa hard, horny mass having good binding qualities. and yet offering noimpediment to usual woodworking operations, such as sawing,

laning, chiseling. and the like. The binder 1s preferably made fromsawdust or somewhat larger particles of raw wood as by crushing orrolling the wood particles between relatively rotating discs whereby thefibers are torn apart and subjected to pressure in the presence ofwater, and ultimately are convertedsubstantially entirely into a thansawdust are used as the raw material for the binder, they are preferablyobtained by chipping, hogging or shredding mili waste or oal, and not bygrinding solid wood on a stone as in pulp making. These chips orparticles advantageously can. be water-logged to facilitate theirvmechanical disintegration and their conversion into gelatinous material.

The filler need not be separate fibers, as excellent results are had byusing bundles of fibers such as sawdust, preferably screened to take outthe finest and the eoarsest particles. Incompletely gelatinized woodparticles can constitute the filler, and it is possible to use groundwood pulp or cooked wood pulp or old newspapers beaten to a pulp as thefiller. but as hereinafter pointed out at length, there are manypractical advantages in using sawdust or equivalent unground andunbeaten fibers grouped together or aggregated as in the living tree.

The details of the process and of the product in their preferredembodiments will be better understood from the following disclosure.

The binder.

Starting with saw mill oti'al or waste, such as slabs. edgings,trimmings, shavings, and even bark or with mixtures of these, orstarting with paper mill offal or waste such as crooked bolts, or limbsor branches such as are commonly left in the forest. either with orwithout preliminary removal of the bark by usual methods. as in the.so-called drum barker, I pass the waste through a hog such as is usedat saw mills for-eutting up waste wood to make it suitable for fuel, orthrough a chipper, such as is used in preparing wood forthe soda,sulfite or sulfate process, or through a coarse shredder, such as issometimes used at saw mills in place of a hog to reduce wood to smallchips or fragments. If desired, a hog and a shredder may be used inconjunction, the hog cutting the wood into fragments say two incheslong, and the. shredder beating these fragments into smaller pieces.Good sound round wood can ot' course be used as raw material butmillwaste is much cheaper and is entirely satisfactory.

I will hereinafter designate as chipping, are carried out by a cuttingaction which requires very much less power than if the waste werereduced to a pulp by holding solid blocks of it against a rapidlyrotating stone as in grinding wood for ground wood pulp. Also, theproduct resulting from chipping. is entirely different from ground woodpulp.

Thus. by ehipping,'the saw mill or paper mill ofal is reduced to a massof chips or Au of these l operations which, for lack of a better name,

wood particles of a size about one-half inch in length by one-eighthinch in diameter, or less. This material is then passed over a series ofscreens and the. very fine particles, which for want ot' a better name Iwill hereina fier designate as liber aggregates, are collected andstored in a bin. These fiber aggregates may be as fine as ordinarysawdust and in fact by starting with sawdust, such as is obtainable atany saw mill I can dispense with the chipping procedure describedabove,.i'or the material is already fine enough to be called fiberaggregates and to be used as such. lIn the drawing, the bin for holdingthe sawdust of other fiber aggregates is marked with reference characterl.

The next coarser grade from the screens, which I prefer to. call smallwood particles, goes ultimately to a storage bin 2, and the coarsestparticles are returned from the screen to the shredder for retrcatmentand ultimate conversion into small wood particles and into the smallerfiber aggregates. lf the saw mill waste is all in the forni of sawdust,or other like small particles, the. chipping and shredding steps can beomitted for the material that is to go into bin 2, the same as for thatsupplied to bin 1.

The small wood particles that are to be supplied to bin 2 can withadvantage be given a water-logging treatment after being taken from thescreen and before being delivered into the bin. If sawdust is to be usedas a raw material, the procedure is the` same. This water-logging 1sused because wood that is wet is very much weaker and can be tornapartwith less expenditure of energy than wood that is dry-the fibersseparate from one another more easily. For example, wet wood has, incompression, about one-halt1 to one-third of the strength of dry wood.This water-logging can be done conveniently by first submerging thesmall wood particles in water heated near or preferably to the boilingpoint, and then, while the wood particles are subn'icrged in a closedtank, subjecting the mass to pressure such as steam pressure to forcethe hot Water into the fiber aggregates.

As an alternative procedure, the small wood particles can he thoroughlyheated in the hot water and then, while the temperature of the water isnear or at the' boiling' point, cold water can be added to causecontraction of the expanded air and gases of the wood particles, therebydrawing water into the pores or voids of the "particles,

As another procedure, the small wood particles while hot from theexposure to hot water, can be dumped into cold water to causecontraction of the expanded air and gases as above described. Under somecircumstances, it is more economical merely to let the hot water and thesubmerged wood particles cool by radiation, for b so doing argequantites of water will be rawn intol the pores and voids of the wood.

By such a treatment, small wood particles (and sawdust) can be so thorouhly saturated with water that they will sin in water in an hour or less.It they were merely submerged in water it would take months and, in thecase of resistant'- woods, years, before the wood soaked up enough watertosink. '.lhe heating in hot water is not intended to be al cookingoperation and-there need be no chemical present to effect cooking.Nevertheless, the hot water dissolves out some or perhaps all of thehighly soluble constituents of the wood.y \Vlien western larch is usedas the wood, this is a valuable feature of the process, because of thepossibility'of recovering valuable sugar-making ingredients from theliquor.

The small wood particles (which, as above explained, may be nothing more'than sawdust or may be larger particles), now thoroughly saturated withwater and consequently in a very weak condition, are passed into hopper2 (Fig. 1) preparatory to delivery iiito a machine 3 whereby they aretorn apart and reduced to separated fibers. Since wood is weaker hotthan cold, l prefer to pass the .small wood particles into this machinewhile they are stillhot from the water-logging procedure.` the chillingwith cold water has completely cooled the Wood pai'ticles,'it issometimes advisable to again heat them up before delivery into inachine3. The machine 3, for separating the fibers, may be constructed in manyways, but

best results have been obtained by me in aii apparatus having two largediscs of metal, one of which is rotatable with respect to the other, andbetween which the hot and water-` logged wood is subjected to a rollingaction to tear, or more strictly speaking, crush the .fibers one fromanother. Good results have been obtained by use of disc grinderscommonly known as corn crackers, of which thc .36 inch single disc millof Bauer Bros. Co., Springfield, Ohio, U. S. A., 'is a goodillustration. The details of such a disc grinder or corn cra-cker arewell illustrated in U.'S. Letters Patent Nos. 565,690, issued August 11,1896, 817,610, issued April 1U, 1906.

In such a machine, the action of tearing the 'wood fibers apartresembles somewhat the disintegrating effect of rolling a match underfoot on the fiooi', excepting, however, that because of theY relativeyrotative movement of the discs, each pieceof wood or bundle of fibershas a gyroscopic motion about the axis of the rotating disc so that notonly are the fibers and bundles of fibers subjected to a. crushingaction, but they are subjected to a twisting effect. As one disc rotateswith respect to the other, the small wood particles or bundles of fiberswill naturally take up positions along radii of the rotating disc. andsince their outer ends travel through a greater distance than theirinner ends, there will he a decided tendency vI'or the fibers to sliplongitudinally with a twisting movement. That is to say, there is notonly a crushing pressure perpendicular to the axes of the individualfibers, but there is a strain, in shear, superimposed on the crushingstrain and parallel to the axes of vthe fibers, or more strictlvspeaking, radial to the rotating plate of the. machine. lt will beunderstood that the two plates of the machine between which theparticles are rolled have slightly concaved faces and can be roughencdor surfaced to accelerate the disintegrating action or fiber liberation.Both plates maj` rotate in opposite directions, or one may be stationaryand the other rotatable. The. working faces of the discs are preferablyof metal; but of whatever material. the surfaces are adjusted in suchmanner that they do not touch. It is also important that means beprovided for adjusting the distances between the plates in accordancewith the size, character and origin of the wood particles undertreatment. and the character of the product desired. It .is a rollingand twisting act-ion rather than a grinding` action that gives bestresults in the manufacture of the products hereinafter described. Toomuch of the grinding action produces too large a percentage of woodflour, as distinguished from fiber pulp.

Thepower consumed for reducing wood to pulp by first chipping, thenshredding and then rolling the small wood particles between tworelatively moving dises as above described, is much less than thatrequired for tearing the fibers apart on an ordinary l paper niillgrindstone; for not only has the (Sil chipping and shredding cut thefibers from the solid wood` but theresistance or strength of theparticles has been reduced by waterlogging and by heating, and,furthermore, the disintegrating or fiber-liberating power is' applied tothe particles in compression and in shear, and there fore along theirlines of least resistance. Also, in this process, friction andfrietional losses have been reduced to a minimum. The bundles of fibersact as rollers between the moving surfaces while rolling` one upon theother'. If desired, water may be passed through the mill with theparticles, but this is to facilitate the flow or flushing out of thematerial and not because of the cooling action of the water. ln fact hotwater can best be used for this purpose because of its effect inlowering the resistance of the wood to crushing action and similardisintegrating stresses. When water is used, or even without the water,it is well not to rotate the mill too fast, for not only is there apower loss due to the inertia of the water and the material beingground, but also there is apt to be a bad effect on the product becauseof too great breakage of individual fibers and too high a production ofwood flour. machine 3 can be screened and the wood particle-sof propersize to be called fiber aggregates can be separated out and deliveredtobin 1 as a substitute for, or an a-dmixture to, the sawdust therein.

To reduce the wood to individual fibers, it may be passed repeatedlythrough the same fiber liberating machine, screens being used t0separate out those fibers that have been sufficiently reduced andreturning to the machine for further treatment only the coarser bundlesor shives. Or, if desired, a series of fiber liberating machines may beused, in each'succeeding one of which the relatively moving surfaces areso adjusted as to give best disintegrating action on the partiallyreduced wood with which it is supplied. The latter procedure ispreferable.

Such an arrangement is indicated diagrammatically in Fig. 2 of thedrawings, where the material delivered from disc grinder 3 is carried byan elevator 4 to a hopper 5 adapted to deliver to a dise grinder 6. Whendelivered from the latter to tank 7, the mass can be lifted by pump 8and delivered through pipes 9 or 10 to grinders 11 or 12, which, inturn, deliver to tank 13 from which the mass can similarly be pumped toother disc grinders of the series. Asthe wood proceeds through theseries of grinders, the particles are torn apart into sepa ateindividual fibers and furthermore these fibers undergo a chemical changeand ultimately are delivered from the last grinder of the series intostorage tank 14 as a gelatinous, structureless mass free from chemicalsof any sort and well adapted for use as a binder in the wall boa rd ofmy present invention. Y

It is well recognized in the literature that the hydration qualities oflignocellulose or wood are not very great, and that mechanical wood pulpsuffers little alteration by beating in a paper-makers beater. But. lhave found that when li gnocellulose or wood is crushed or rolled underpressure in a corn cracker. hydration will begin even in the first millof the series, and the hydration will progressively increase as the woodis reduced to fiber and the fibers are broken and crumbled underpressure. The waterlogging treatment to which the wood has beensubjected facilitates hydration. Furthermore, the wood hydrates andapproaches gelatinization more easily while it is warm or hot. However,it is entirely possible to produce gelatinized lignocellulose withoutgiving it the water-logging treatment and by rolling and breaking thefibers in cold water instead of hot.

The material delivered from i titl While the hydration or gelatinizineiect may not be very great in grinder 3 ig. 2),

. the other, and particularly thel last grinders of the series, in whichthe plates are set close to ether so completely c`omb out, crush and igeatinize the wood fibers, that their fibrous and as appears below, Athephysical structure is likewise radically different. Therefore, for lackof a better name, I ,have herein designated this material, which is tobe the binder or bindingelement of the wall board, as gelatinizedlignocellulose. Gelatinized lignocellulose, as the term is herein used,means wood fibers (lignocellulose) that have been so treatedmechanically as to be completely torn and broken so thattheir length isbut a fractional part of their origina] length, say for instance,one-tenth or less; furthermore, the original wood cellulose has beenchanged chemlcally, though only by mechanical treatment in the presenceof water, and perhaps to the..extent of adding to it an unknown numberof water molecules. The material, when wet, is a slime which on dryingshrinks enormously and is inclined to warp and forms a dense hardbone-like mass of considerable strength and without appreciable fibrousstructure but inclined to split or flake, and of a color usuallysomewhat darker than that of the wood from which it was made. Made frompine, spruce, or' hemlock, the material is cream colored, and made fromlir, tamarack or larch, it is somewhat darker in color. -It can be madereadily from any of these woods, and others, but with cedar the problemis more diilijcult because of difficulties in chemically changing thewater-resistant fibers of such a gymnosperm. To gelatinizewater-resistant fibers, such as cedar, I lind it expedient to supply thegrinders, not with water, but with an aqueous solution of sodiumsilicate. This is not so cheap as water alone and yields a final productthat may not be entirely free from chemical additions, and thereforemore likely to change in color, or otherwise, while in use as on thewall of a building.

Vhen properly made, the gelatinized lignocellulose contains no spindleshaped .fibers of their original length, nor bundles of cut fibers, suchas is found in wood Hour. Both physically and chemically, gelatinizedlignocellulose is readily distinguishable from Wood Ilour, thoughaccording to my experirated in the above describedv process of makinggelatinized lignocellulose is the recirculation of thc water in some, atleast, of the liber-liberating machines which, with the soluble materialin the wood, can be recovered in a manner similar to that described inmy U. S. Patent No. 1,339,489, issued May ll, 1920. Furthermore,whenever a plurality of fiber liberating machines are used in series .toprogressively reduce the Wood particles to pulp, and' then to gelatinizethe pulp, the circulation of the water to take out soluble material (asfrom western larch), can be 0n the counter-current principle, that is tosay, the water used in the last machine or grinder of the series can befiltered off from the pulpy material delivered therefrom and `-can beintroduced as the flushing Water of the machine next preceding, and soon throughout the series, the lstrongest solution of solubleconstituents being drawn off from the partially disintegrated shreddedwood particles of the machine into which these particles initially weredelivered.`

The filler.

Stored in bin 1 is the filler for the board. As above explained, thismaterial may be sawdust or may be the finer particles obtained byscreening material from the shredder, or may have been obtained byscreening thei material delivered from. one of the grinders. I havecalled these smallest wood particles ber aggregates, and by fiberaggregates I mean fiveormore wood fibers still joined together as inAthe living tree. The. fibers need .no t,. however, .be of full length,and in the caseof sawdust, often are not. Shingle sawdust is veryl goodlraw material for use as a-fillcr after the very fine and the verycoarse particles have been screened out. This sawdust is slivery incharacter, light in weight, and durable, and has the furthercharacteristic, particularly if made from cedar, that it does nothydrate during mixing nor while in use.

Instead of using a. dry filler, such as sawdust, the filler may beobtained from other sources. For instance` it may consist of a part ofthe output of one or more of the grinders or gelatinizers abovedescribed, or of coarse particles screened fromthe output of one or moreof those elatinizers, and may be in the wet condition 1n which it camefrom the elatinizers. Such incompletely gelatinized ignocellulose isin-fact a mixture of completely gelatinized and structureless wood withwood fibers and aggregates that have been gelatinized on the surface.Such a material blends well with the completely gelatinized andstructureless binder and of course is cheap, for it can be made of sawmill offal with the expenditure of but little power.

But instead of using fiber aggre ates in whole or in part, as abovedescribe I can use a more expensive filler, such as ground wood pulp, orcooked wood pulp, or mixtures of these; or I can beat up newspapers andother paper waste in a beater and use the resultant pulp, but none ofthese substitute fillers is as satisfactory for m purpose as fiberaggregates, such as saw ust or the incompletely disintegrated product ofone of the early grinders of the series, and none of them givesa wallboard that is as easy to dry, is as free from shrinkage, has asbeautiful a surface, nor is as good a sound and heat insulator, as whenber agigregates are used as the filler of the boar The The next step inthe production of the wall board consists in mixlng the gelatinizedlignocellulose with the filler. The latter, as above explained, mayconsist wholly, or in large part, of wood fiber aggregates of the 4samekind of wood, and even of the same origin as that which went into thegelatinizers. Or the ller may be a different wood, as for instance, onenot easily gelatinized by grinding in water such as cedar or aspen. Tobring the gelatinized lignocellulose and the wood ber aggregates intointimate contact and to insure a mass uniform throughout, I pump theslimy gelatinized lignocellulose into a mechnical mixer 15, consistingof a metal trough, set at a slight incline, and provided wtih a powerdriven stirrer, comprising a central shaft on which are mounted a seriesof inclined stirring blades or paddles. The liber aggregates are fed tothis from hopper l, and water may be added to thin the mix.

The relative proportions of the several ingredients of the mixture maybe varied through relatively vide limits. Up to a certain point, thelarger the percentage of gelatinized lignocellulose, the stronger is theresultant board. The board should contain 25% or more by dry woodweightl of the gelatinized lignocellulose and 30% or more by dry woodweight of fiber aggregates. A mixture composed of gelatinizedlignocellulose and 40% fiber aggregates, by dry 'wood wei ht, to whichenough water has been adde to make the mass flow readily,

gives a very strong, stili' and satisfactory wall board. Cedar sawdustis satisfactory as a filler, though not readily adapted to themanufacture of the binder. Spruce or pine give a stronger board thancedar.

The

These materials may be omitted entirelyy when water-proofing is notdesired, Without lmpalrmg the strength or other characteristics of theboard excepting that of its resistance to water. Normally, the percentaeof sodium resinate may be from two to eiglit per cent of the dry weightsof the other components, depending on the kind of wood used andparticularly its resinous content, and the degree of waterproofingdesired in the iimshe product. The quantity of alum is 1n proportion tothe sodium resinate, due allowance being made for the amount of waterpresent, etc.

If a ireproof board is desired, the requisite amount of ammonium sulfatecan be added to the batch while in the mixer.

A non-mineral coloring, such as an aniline dye, can also be added, if acolored board is desired. This is particularly advantageous when theboard is to be finished in imitation of mahogany. u I

Another treatment consists in coloring the gelatlnized lignocelluloseone colo'r` and the filler a different shade or color. This gives a.very pleasing product.

Pressing.

tain a constant head in the box with an over` A iow into an undergroundstorage tank 18- (Fig. l). A constant stream of the pulpy mass flows outof a horizontal slot in the side of the box under a gate 19. This gateis provided with a ra'ck and pinion 20, 'by which it may be raised orlowered to vary the size of the stream. As the thick mixture y Howsthrough the slot it is delivered in a uniformly thick layer on atraveling canvas belt or conveyor 2l which is mounted on cylinders 22and 23 and is reinforced along its upper stretch by underlying and powerdriven endlesstraveling screens 24 and 25 suitably supported on drumsand rollers` This prevents sagging of the canvas belt while its load ofmaterial is being ldelivered to :md from the ress. To make a board about,36 thick, t ie thickness of this layer as it flows onto the canvas'beltis approximately 213- inches.

The width of the canvas belt corresponds with the length of the board orpanelto be made, and the cellulosie mass is prevented from iowing oi thesides of the belt by means of two stationary baiiles 26 and 27 (Fig. 2).These baiiies are adjustablelaterally to accommodate various widths ofcellulosic mass,y to accord with changes in the len th ofthe boards tobe made. In genera a board length of sixteen feet is suitable forordinary trade delnands. Thus the cellulosic mass in a relativel thickand uni form layer sixteen feet wi e and one inch thick on the canvasbelt is carried forward between the stationary side barriers 26 and 27and ultimately passes between the platens of a hydraulic press. Thelcanvas belt moves forward with an intermittent movement and as soon asthe roper amount of the mass is between the p atens, a rectangular die28 having inside dimensions corresponding to the size of the board to bemade, is lowered into the mass until it rests on the canvas sheet. lThecellulosic mass is so fluid that it readily movesaside to permit thislowering of the die. Then the upper platen, which fits within the diewith a substantially water tight joint, is lowered into the die andcompresses the cellulosic mass,`

whilef simultaneously squeezing its excess water both upward anddownward through suitable slots in the platens. The platens thenseparate, the die lifts, and thebelt moves forward until a fresh amountof material has passed between the platens, when the operation justdescribed is repeated. This entire operation is done mechanically andless time than a minute is needed to press each sheet.

In order to prevent that part of the cellulosic mass which has not beenpressed from flowing onto the compressed mass after the platens havebeen released, there are provided a `series of cross baffles or'partitions 31, adjustably attached between t'wo sprocket chains 32 whichare driven by a power driven sprocket and pass over guide wheels 34, 35and 36 as shown. These baffles or partitions, which may be made of Wood,press down into the soft watery nia-ss before it reaches the press andblock it off into rectangles of approximately the size needed at lthepress. Because of these cross baiiies 31 and the side barriers 26 and 27there is no necessity for using trays in which to form and press theboards.

I Drying.

Thecompressed cellulosic mass-is carried forward from the press on thecanvas belt and\when picked up from this belt by an endless conveyor 37is in the form of a damp but. fairly stiff compressed sheet. Conveyor 371s adjustable vertically in sup rts 38 to `transfer the compressed sheetsic ewise into a dry kiln 39. This kiln may be oit'. the tunnel typeheated by steam coils and provided wlth well known means for regulatingthe circulation of air, its humidity, temperature, etc., to secure mosteffective and uniform drylng action and to lessen such tendency as theremay be for warpage of the boards.

The dry kiln removes the water from the boards so that they emerge fromthe kiln, dry, stiff and hard. 'i

Finishing.

The boards are nextrun through saws and cut to desired size or .shapeand in that form are marketable in place of wall board made by usualprocesses. The boards may be nalled directly to the Astudding of abuild-.lng to serve in place of lath and plaster, and like wall board now onthe market, may be sawed and similarly cutto meet the needs of thebuilder.. But unlike wall boards of more usual manufacture, they do notcontain enough sodium silicate or other mineral to be harmful to the.saws andother edge tools of the carpenter. On the contrary, the tconsist throughout of substantiall not ing but woody material throughwhich a saw or chisel will work as lreadily as through solid wood andwith no more in- ]ury to the edge of the tool. The rosin size `and theammonium sulfate, if present, are

not harmfulv to edge tools.-

.But in many respects this new 4product is different from wall boardmade from paper sheets cemented together, for, if desired, the

wall board of the present invention maygbe' passed through an ordinarywood planer tov fimsh the surface, or through a sandma chine to dressits surface, or betweenA steel. rolls to glve the surface either a highpolish l or to impress 1n or on the surface patterns.

or designs or to give a finish similarvto burlap or canvas. Likewise,the finished and even polished face of vthe board may be treated much assheet steel is now treated to give it the appearance of grained mahoganor other woods. The surface can be painted and decorated much as can bedone with' solid wood, excepting that it has not the characteristicgrain of wood, but on the contrary, if made with ber aggregates, has

a uniform and pleasin mottled appearance not unlike the so-calledDoatmeal Wall pa ers. AS above indicated. the process by W iich thisnovel and valuable product is made, may vary in many of its details,both as 'to the origin of the raw materials and as to the, procedure bywhich those materials are treated to bring them into proper physical andchemical condition to unite under pressure and kiln drying into theproduct described in detail above. It is of particular importance,however, that no chemical need be used in the process and that wateralone, together with suitable mechanical manipulations, such as cutting,rollin", and twisting, properly repeated, is lsufficient to convert sawmill oi'al such as slabs. edgings, trimmings, sawdust, shavings, andeven bark, into a readily marketable product and with relatively lowpower consumption. As a permissible variation from the preferred methodabove described, I may proceed by chipping saw mill oii'al such asslabs, edgings, trimmings, shavings, or bark. orf/paper makers waste,such as crooked bolts, sa-plings, and the limbs and branches ordinarilyleft in the forest, and then mechanically disintegrating the chippedwood by grinding or, more strictly speaking, crushing, in a disc grinderin the presence of water, preferably hot. water, as above described, andwith or without the preliminary water-logging, and stopping thisInechanical disintegration before the fiber aggregates are completelyreduced to a structureless gelatinized mass. For instance`I l can carrythe wood through less than six grindings and obtain a mixture consistingin part, say 60%, of completely gelatinized material and in part, sav40%, of wood fibers and fiber aggregates which have been gelatinized onthe surface but are of woody character at the core. The exact number ofgrindings requisite for the desired result depends on many factors, suchas the character of' the wood and whether it is highly resistant towater, Whether it has been water-logged before grinding, how closetogether the grinding plates have been set and whether hot water hasbeen used in the grinders` etc. But roughly stated, three or .four watergrindings as above described will yield a product approximately half ofwhich is in a gelatinized condition, and the other half' of whichconsists of fibers and fiber aggreates with but a surfacegelatinization. uch a mixture, when delivered from the grinders, can bepumped into mixer l5 and thereafter can be sized, fireproofed, and thenflowed out in a sheet for pressing, drying and finishing in much thesame way as il' sawdust or equivalent dry fiber aggregates were used asa filler with a completely gelatinized binder. This alternativeprocedure, though permissible, is in my present opinion not so good asthat first described,

and yields a product having the disadvantages that it is not so cheap,not so attraetive, not so good as a heat or sound insulator (because ofthe relative absence of voids and air pockets), more inclined to shrinkand warp on drying, not so easy to dry, and not so light in weight.Also, a board so made has a monotonous appearance quite in contrast withthe beautiful mottled or composite appearance resulting from the'use offiber aggregates that have not been broken up by passage through a discgrinder.

As a still further permissible variation, an incompletely gelatinizedmass of fiber aggregates mechanically disintegrated by grinding orcrushing in the presence of water, as above described. can be used as abinder for a filler consisting essentiall of unground fiber aggregatessuch as sawcust,

due care being taken to keep the proportionl of binder to filler withinthe ranges dictated by the requirements of strength, freedom rIpmwarping, undue shrinkage and the Preferably, the mass as it reaches thepress, should comprise at least by dry wood weight of mechanicallygelatinized lignocellulose, and preferably as much as 4057 to 60%.Likewise, the mass should contain as much as or more by dry weight offiber aggregates and preferably as much as to 40%.

The apparatus whereby the process is carried out. obviously ma vary indetails without fundamentally a tering either the process or the productclaimed herein'.

ovel features of the apparatus will be claimed in a separateapplication.

I claim 1. The method of making wall board which consists inmechanically disintegrab,

ing small wood fibers to form a gelatinous mass, incorporating therewitha fibrous filler and then pressing and drying the mass.

2. The method of making` wall board which consists in mechanicallydisintegrating a cellulose containing material to form a gelatinousmass, incorporating therein fiber aggregates to the extent of 30% to 60%by dry Weight, and then pressing and drying the mass.

3. The method of making Wall board which consists in mechanicallydisintegrating small `wood particles to form a'gelatinous mass, mixingfiber aggregates therewith to the extent of about 50% by dry WoodWeight, and then pressing and drying, substantially as described.

4. The method of making- Wall board, which consists in water-loggingsmall wood particles, crushing and rolling said particles While Wetbetween relatively rotating discs until substantially converted intogelatinous llo lignocellulose, mixing fiber aggregates theref with,shaping and pressing into a board, and drying and finishing the board,substantially as described.

'drying and finishing the board, substantially as described.

6. The method of making wall board, which consists lin chipping saw millofi'al, forming small wood particles therefrom, water-logging saidparticles, crushing and rolling said particles while wet betweenrelatively rotating discs until converted into gelatinouslignocellulose, mixing therewith an approximately equal amount by dryweight of ber aggregates, sizing and fireproofing the mixture, shapingand pressing the mixture into a board, and drying and finishing theboard, substantially as described.

7. The method of making wall board, which consists in chipping saw milloial, forming small wood particles therefrom,

water-logging said particles, repeatedly Y, crushing and rolling saidparticles in hot water between relatively rotating discs until convertedinto gelatinous lignocellulose, mixing therewith an ap roximately equalamount by dry weight ci) sizing and fireproofing the mixture, dilutingwith water, flowing into a layer, pressing the layer into a board, anddrying and f finishing the board, substantially as described.

8..A wall board consistin essentially of a binder and a filler, theginder being ,a dried gelatinous ymass of mechanically disintegratedlignocellulose.

' 9. A wall board consisting essentially of a binder and a filler, thebinder being a dried gelatinous mass of mechanically disintegratedlignocelluloseand the filler being essentially fibrous.

10. A wall board consisting essentially oly a binder and a filler, 'thebinder being a dried gelatinousmass of mechanically disintegrated liocellulose and the filler consisting essentially of fiber aggregates.

fiber aggregates,I

11'. A wall. boardV consisting essentially of a binder and a ller, thebinder being a dried gelatinous mass of mechanically disintegratedlignocellulose, and the filler consisting of untreated sawdus't.l

12. A wallboard consisting essentiall of a binder and a filler, thebinder being a ried gelatinous mass of mechanically disintegratedlignocellulose, and the filler consisting essentially of fiberaggregates, said board being sized uniformly throughout, substantiallyas described.

13. A wall board consisting essentially of a binder anda filler, thebinder being a dried gelatinous mass of mechanically disintegratedlignocellulose, and the filler consisting essentially of fiberaggregates, said board being fireproofed uniformly throughout,substantially as described.

414. A`wall board consisting essentiall of a binder and a filler, thebinder being a ried gelatinous mass of mechanically disintegratedlignocellulose, and the filler consisting essentially of fiberaggregates, said board being dyed, substantially as described.

15. A/wall board consisting essentially of a binder and a filler, thebinder being a dried gelatinous mass of mechanically disintegratedlignocellulose and the filler consisting essentially of fiberaggregates, said y binder being dyed one color and said filler being ofa different color.

16. A wall board consisting essentially of -a binder and a filler, thebinder being a dried gelatinized4 mass of mechanically disintegratedlignocellulose and the filler consisting essentiall of fiber aggregates,said binder ybeing yed one shade and said filler being Adyed a differentshade.

17. A .wall board consisting essentialflly of a binder and a filler, theb inder being a' ried gelatinized mass of mechanicall disintegratedlignocellulose from saw mi oial.

18. A wall board consisting essentially of a Ybinder and a filler, thebinder being a dried gelatinized mass of mechanically disintegrated linocellulose prepared from saw mill oi'al an the filler consistingessentially of fiber aggre ates.

19. A wa l board consisting essentiall of a binder and a filler, thebinder being a ried gelatinous mass of mechanically disinte ated liocellulose from saw mill oial an the fille consisting of untreatedsawdust.

. In testimony whereof I aix my si ature.

HOWARD F. W ISS.

